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United States Patent | 6,004,298 |
Levander | December 21, 1999 |
A piston rod for use in an injection device for an injection cartridge is provided with a single or multiple thread along a predetermined portion of its length, after which the thread changes into a longitudinal groove for each thread, such that a turning movement of the piston rod will turn into an axial movement after the predetermined length. The thread is shaped as one or more helicoidal grooves in the surface of the piston rod, the grooves turning into the longitudinal grooves after the predetermined length. A nut element cooperates with the thread and includes at least one radial inwardly directed projection for each thread, the projection or projections guiding the piston rod by the groove or grooves forming the thread.
Inventors: | Levander; Gustav (Bromma, SE) |
Assignee: | Pharmacia & Upjohn Aktiebolag (Stockholm, SE) |
Appl. No.: | 976104 |
Filed: | November 21, 1997 |
Oct 29, 1993[SE] | 9303568 |
Current U.S. Class: | 604/211; 604/224 |
Intern'l Class: | A61M 005/50 |
Field of Search: | 604/91,208,224,210,211,209,228,234 |
4874381 | Oct., 1989 | Vetter | 604/91. |
5080649 | Jan., 1992 | Vetter | 604/91. |
5137514 | Aug., 1992 | Ryan | 604/224. |
5591136 | Jan., 1997 | Gabriel | 604/224. |